The present invention generally relates to microscopes, and specifically relates to microscope stands which have a lens turret rotatingly mounted thereon such that the objective lens which is furthest from the microscope stand is in its vertical working position.
In prior art microscopes of this type, the lens turret has a number of objective lenses mounted on the turret at an angle with respect to the axis of rotation of the turret. Therefore, the axis of rotation of the turret is always displaced with respect to the vertical which is the working position of the objective lens being used. In the type of microscope in which the working objective lens is the furthest from the lens stand, the stand protects the unused lenses from inadvertent damage. In order to accommodate the axis of rotation of the lens turret, the turret is mounted on a planar surface which in cross section increases in thickness towards its front surface.
With the increasing thickness towards its front surface necessary to provide the proper mounting angle for the lens turret, there is always a portion of the microscope stand which has a relatively small thickness and is generally an angular discontinuity at the lower edge of the stand. The combination of the angular discontinuity and the very thin thickness at this point contribute to a substantial reduction in the rigidity of the lens holder. To compensate for this weaker stand, the minimum thickness of the stand at this weaker point must be substantially increased with the result that the lens turret is located at a substantially further distance from the eyepiece. Because of this increased distance between the objective lens (on the lens turret) and the eyepiece, an additional lens (called a tube lens) must be inserted into the beam path.
The utilization of a tube lens adversely affects both the light flux and the techniques for optical correction in a precision microscope. Furthermore, the use of such a tube lens involves higher costs both for the lens and its mounting structure and its installation. This is especially true when the microscope is equipped with a plurality of objective lenses and eyepieces which are designed for use in a simple microscope (one without a tube lens).